Receiver with multi-spectrum parallel amplification

ABSTRACT

A radio receiver has a front end having a shared amplification path for both radio frequency signals and intermediate frequency signals. In one example, the shared amplification path can include a low noise amplifier and an attenuator. By amplifying both radio frequency (RF) signals and intermediate frequency (IF) signals with the same shared amplification path, gains in power efficiency, and reductions in cost and circuit size can be achieved.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation application of U.S. application Ser.No. 14/466,307, filed Aug. 22, 2014, titled RECEIVER WITH MULTI-SPECTRUMPARALLEL AMPLIFICATION, the entirety of which is incorporated byreference herein.

This application is related to applications titled RECEIVER WITHMULTI-SPECTRUM PARALLEL AMPLIFICATION, Ser. No. 14/466,275, filed Aug.22, 2014, now U.S. Pat. No. 9,356,639 and RECEIVER WITH MULTI-SPECTRUMPARALLEL AMPLIFICATION, Ser. No. 14/466,368, filed Aug. 22, 2014, nowU.S. Pat. No. 9,246,664, the disclosures of each of which are herebyincorporated by reference in their entireties herein.

BACKGROUND Field of the Invention

The invention generally relates to electronics. In particular, theinvention relates to receiver front-end circuits.

Description of the Related Art

Various receiver architectures exist. These architectures includeregenerative receivers, direct-conversion receivers, and superheterodynereceivers. Each has its benefits and disadvantages.

One disadvantage of a conventional superheterodyne receiver architectureis that the active component count can be rather high, which can resultin a relatively large, expensive, and power-hungry circuit. What isneeded is an improved superheterodyne receiver.

SUMMARY OF THE DISCLOSURE

The invention includes a radio receiver front end having a sharedamplification path for both radio frequency signals and intermediatefrequency signals.

One embodiment includes an apparatus, wherein the apparatus includes: afirst N-plexer arranged to perform frequency multiplexing, the firstN-plexer comprising: a first port configured to receive signal(s)comprising one or more signals of a radio frequency (RF) band; a secondport configured to receive signal(s) comprising one or more signals ofan intermediate frequency (IF) band; and a third port configured toprovide signals comprising the one or more signals of the RF band andthe one or more signals of the IF band; wherein the first N-plexer isconfigured to substantially isolate the one or more signals of the IFband from the first port; a shared amplification path having an inputnode and an output node, wherein the input node is coupled to the thirdport of the first N-plexer, the shared amplification path comprising: afirst amplifier; and a controllable attenuator arranged in series withthe first amplifier; wherein the shared amplification path is configuredto amplify at least both RF signals and IF signals; a second N-plexerarranged to perform frequency demultiplexing, the second N-plexercomprising: a first port coupled to the output node of the sharedamplification path to receive signals comprising one or more amplifiedsignals of the RF band and one or more amplified signals of the IF band;a second port configured to provide signal(s) comprising one or moreamplified signals of the RF band; and a third port configured to providesignal(s) comprising one or more amplified signals of the IF band,wherein the first port, the second port, and the third port aredifferent ports; a mixer configured to multiply a local oscillator (LO)signal with signal(s) comprising the one or more amplified signals ofthe RF band to generate a plurality of signals including the one or moresignals of the IF band; and an IF filter arranged in a signal pathbetween an output of the mixer and the second port of the firstN-plexer, wherein the IF filter is configured to filter the plurality ofsignals to extract the one or more signals of the IF band and to providethe one or more signals of the IF band to the first N-plexer.

One embodiment includes a method of amplifying a plurality of signals,the method including: receiving signal(s) comprising one or more signalsof a radio frequency (RF) band at a first port of a first N-plexer;receiving signal(s) comprising one or more signals of an intermediatefrequency (IF) band at a second port of the first N-plexer; frequencymultiplexing the signals of the RF band and the IF band to generatemultiplexed signals; providing the multiplexed RF and IF band signals ata third port of the first N-plexer; amplifying the multiplexed RF and IFband signals in a shared amplification path to generate one or moreamplified signals of the RF band and one or more amplified signals ofthe IF band, wherein the shared amplification path comprises a firstamplifier and a controllable attenuator arranged in series with thefirst amplifier; receiving signals comprising the one or more amplifiedsignals of the RF band and the one or more amplified signals of the IFband at a first port of a second N-plexer; frequency demultiplexing theone or more amplified signals of the RF band and the one or moreamplified signals of the IF band using the second N-plexer; providingsignal(s) comprising one or more amplified signals of the RF band at asecond port of the second N-plexer; providing signal(s) comprising oneor more amplified signals of the IF band at a third port of the secondN-plexer; mixing a local oscillator (LO) signal with signal(s)comprising the one or more amplified signals of the RF band to generatea plurality of signals including the one or more signals of the IF band;and filtering the plurality of signals to extract the one or moresignals of the IF band and providing the one or more signals of the IFband to the first N-plexer.

One embodiment includes an apparatus for amplifying a plurality ofsignals, the apparatus including: a means for frequency multiplexingconfigured to: receive signal(s) comprising one or more signals of aradio frequency (RF) band at a first port; receive signal(s) comprisingone or more signals of an intermediate frequency (IF) band at a secondport; and provide signals comprising the one or more signals of the RFband and the one or more signals of the IF band at a third port; whereinthe frequency multiplexing means is configured to substantially isolatethe one or more signals of the IF band from the first port; a sharedamplification path having an input node and an output node, wherein theinput node is coupled to the third port of the frequency multiplexingmeans, the shared amplification path comprising a first amplifier and acontrollable attenuator arranged in series with the first amplifierwherein the shared amplification path is configured to amplify at leastboth RF signals and IF signals; a means for frequency demultiplexingconfigured to: to receive signals comprising one or more amplifiedsignals of the RF band and one or more amplified signals of the IF bandat a first port; to provide signal(s) comprising one or more amplifiedsignals of the RF band at a second port; and to provide signal(s)comprising one or more amplified signals of the IF band at a third port;a mixer configured to multiply a local oscillator (LO) signal withsignal(s) comprising the one or more amplified signals of the RF band togenerate a plurality of signals including the one or more signals of theIF band; and an IF filter arranged in a signal path between an output ofthe mixer and the second port of the frequency demultiplexing means,wherein the IF filter is configured to filter the plurality of signalsto extract the one or more signals of the IF band and to provide the oneor more signals of the IF band to the frequency multiplexing means.

One embodiment includes an apparatus, wherein the apparatus includes: afirst N-plexer arranged to perform frequency multiplexing, the firstN-plexer comprising: a first port configured to receive signal(s)comprising one or more signals of a first radio frequency (RF) band; asecond port configured to receive signal(s) comprising one or moresignals of a first intermediate frequency (IF) band; and a third portconfigured to provide signals comprising the one or more signals of thefirst RF band and the one or more signals of the first IF band; whereinthe first N-plexer is configured to substantially isolate the one ormore signals of the first IF band from the first port; a sharedamplification path having an input node and an output node, wherein theinput node is coupled to the third port of the first N-plexer, whereinthe shared amplification path comprises an amplifier configured toamplify signals from at least both the first RF band and the first IFband; a second N-plexer arranged to perform frequency demultiplexing,the second N-plexer comprising: a first port coupled to the output nodeof the shared amplification path, the first port configured to receivesignals comprising the one or more amplified signals of the first RFband and the one or more amplified signals of the first IF band; asecond port configured to provide signal(s) comprising the one or moreamplified signals of the first RF band; and a third port configured toprovide signal(s) comprising the one or more amplified signals of thefirst IF band, wherein the first port, the second port, and the thirdport are different ports; a mixer configured to multiply a localoscillator (LO) signal with signal(s) comprising the one or moreamplified signals of the first RF band to generate a plurality ofsignals including the one or more signals of the first IF band; a firstcontrollable attenuator arranged in a signal path between the secondport of the second N-plexer and an input of the mixer, wherein the firstcontrollable attenuator is configured to set an overall gain of the oneor more amplified signals of the first RF band; and a first IF filterarranged in a signal path between an output of the mixer and the secondport of the first N-plexer, wherein the first IF filter is configured tofilter the one or more signals of the first IF band and to provide theone or more signals of the first IF band to the first N-plexer.

One embodiment includes a method of amplifying a plurality of signals,wherein the method includes: receiving signal(s) comprising one or moresignals of a first radio frequency (RF) band at a first port of a firstN-plexer; receiving signal(s) comprising one or more signals of a firstintermediate frequency (IF) band at a second port of the first N-plexer;frequency multiplexing the signals of the RF band and the IF band togenerate multiplexed signals; providing the multiplexed RF and IF bandsignals at a third port of the first N-plexer; amplifying themultiplexed RF and IF band signals in a shared amplification path togenerate one or more amplified signals of the RF band and one or moreamplified signals of the IF band, wherein the shared amplification pathcomprises, wherein the shared amplification path comprises an amplifier;receiving signals comprising the one or more amplified signals of thefirst RF band and the one or more amplified signals of the first IF bandat a first port of a second N-plexer; frequency demultiplexing the oneor more amplified signals of the first RF band and the one or moreamplified signals of the first IF band using the second N-plexer(112/812); providing signal(s) comprising the one or more amplifiedsignals of the first RF band at a second port of the second N-plexer;providing signal(s) comprising the one or more amplified signals of thefirst IF band at a third port of the second N-plexer at a third port ofthe second N-plexer, wherein the first port, the second port, and thethird port are different ports; controlling a first attenuator to set anoverall gain of the one or more amplified signals of the first RF band;mixing a local oscillator (LO) signal with signal(s) comprising the oneor more amplified signals of the first RF band to generate a pluralityof signals including the one or more signals of the first IF band; andfiltering the one or more signals of the first IF band and providing theone or more signals of the first IF band to the first N-plexer.

One embodiment includes an apparatus for amplifying a plurality ofsignals, wherein the apparatus includes: a means for frequencymultiplexing configured to: receive signal(s) comprising one or moresignals of a first radio frequency (RF) band at a first port; receivesignal(s) comprising one or more signals of a first intermediatefrequency (IF) band at a second port; and provide signals comprising theone or more signals of the first RF band and the one or more signals ofthe first IF band at a third port; wherein the frequency multiplexingmeans is configured to substantially isolate the one or more signals ofthe first IF band from the first port; a shared amplification pathhaving an input node and an output node, wherein the input node iscoupled to the third port of the frequency multiplexing means, whereinthe shared amplification path comprises an amplifier configured toamplify signals from at least both the first RF band and the first IFband; a means for frequency demultiplexing configured to: to receivesignals comprising the one or more amplified signals of the first RFband and the one or more amplified signals of the first IF band at afirst port; provide signal(s) comprising the one or more amplifiedsignals of the first RF band at a second port; and provide signal(s)comprising the one or more amplified signals of the first IF band at athird port, wherein the first port, the second port, and the third portare different ports; a mixer configured to multiply a local oscillator(LO) signal with signal(s) comprising the one or more amplified signalsof the first RF band to generate a plurality of signals including theone or more signals of the first IF band; a first controllableattenuator arranged in a signal path between the second port of thefrequency demultiplexing means and an input of the mixer, wherein thefirst controllable attenuator is configured to set an overall gain ofthe one or more amplified signals of the first RF band; and a first IFfilter arranged in a signal path between an output of the mixer and thesecond port of the frequency demultiplexing means, wherein the first IFfilter is configured to filter the one or more signals of the first IFband and to provide the one or more signals of the first IF band to thefrequency demultiplexing means.

One embodiment includes an apparatus, wherein the apparatus includes: afirst N-plexer arranged to perform frequency multiplexing, the firstN-plexer comprising: a first port configured to receive signal(s)comprising one or more signals of a first radio frequency (RF) band; asecond port configured to receive signal(s) comprising one or moresignals of a first intermediate frequency (IF) band; and a third portconfigured to provide signals comprising the one or more signals of thefirst RF band and the one or more signals of the first IF band; whereinthe first N-plexer is configured to substantially isolate the one ormore signals of the first IF band from the first port; a sharedamplification path having an input node and an output node, wherein theinput node is coupled to the third port of the first N-plexer, whereinthe shared amplification path comprises an amplifier configured toamplify signals from at least both the first RF band and the first IFband; a second N-plexer arranged to perform frequency demultiplexing,the second N-plexer comprising: a first port coupled to the output nodeof the shared amplification path, the first port configured to receivesignals comprising the one or more amplified signals of the first RFband and the one or more amplified signals of the first IF band; asecond port configured to provide signal(s) comprising the one or moreamplified signals of the first RF band; and a third port configured toprovide signal(s) comprising the one or more amplified signals of thefirst IF band, wherein the first port, the second port, and the thirdport are different ports; a mixer configured to multiply a localoscillator (LO) signal with signal(s) comprising the one or moreamplified signals of the first RF band to generate a plurality ofsignals including the one or more signals of the first IF band; a firstcontrollable attenuator in a signal path downstream of the third port ofthe second N-plexer, wherein the first controllable attenuator isconfigured to set an overall gain of the one or more amplified signalsof the first IF band; and a first IF filter arranged in a signal pathbetween an output of the mixer and the second port of the firstN-plexer, wherein the first IF filter is configured to filter the one ormore signals of the first IF band and to provide the one or more signalsof the first IF band to the first N-plexer.

One embodiment includes a method of amplifying a plurality of signals,wherein the method includes: receiving signal(s) comprising one or moresignals of a first radio frequency (RF) band at a first port of a firstN-plexer; receiving signal(s) comprising one or more signals of a firstintermediate frequency (IF) band at a second port of the first N-plexer;frequency multiplexing the signals of the RF band and the IF band togenerate multiplexed signals; providing the multiplexed RF and IF bandsignals at a third port of the first N-plexer; amplifying themultiplexed RF and IF band signals in a shared amplification path togenerate one or more amplified signals of the RF band and one or moreamplified signals of the IF band, wherein the shared amplification pathcomprises, wherein the shared amplification path comprises an amplifier;receiving signals comprising the one or more amplified signals of thefirst RF band and the one or more amplified signals of the first IF bandat a first port of a second N-plexer; frequency demultiplexing the oneor more amplified signals of the first RF band and the one or moreamplified signals of the first IF band using the second N-plexer(112/812); providing signal(s) comprising the one or more amplifiedsignals of the first RF band at a second port of the second N-plexer;providing signal(s) comprising the one or more amplified signals of thefirst IF band at a third port of the second N-plexer at a third port ofthe second N-plexer, wherein the first port, the second port, and thethird port are different ports; controlling a first attenuator to set anoverall gain of the one or more amplified signals of the first IF band;mixing a local oscillator (LO) signal with signal(s) comprising the oneor more amplified signals of the first RF band to generate a pluralityof signals including the one or more signals of the first IF band; andfiltering the one or more signals of the first IF band and providing theone or more signals of the first IF band to the first N-plexer.

One embodiment includes an apparatus, wherein the apparatus includes: afirst N-plexer arranged to perform frequency multiplexing, the firstN-plexer comprising: a first port configured to receive signal(s)comprising one or more signals of a first radio frequency (RF) band andone or more signals of a second RF band; a second port configured toreceive signal(s) comprising one or more signals of a first intermediatefrequency (IF) band; a fourth port configured to receive signal(s)comprising one or more signals of a second IF band; and a third portconfigured to provide the signals of the first and second RF bands andthe signals of the first and second IF bands in a frequency multiplexedfashion; wherein the first N-plexer is configured to substantiallyisolate the one or more signals of the first and second IF bands fromthe first port; a shared amplification path having an input node and anoutput node, wherein the input node is coupled to the third port of thefirst N-plexer; a second N-plexer arranged to perform frequencydemultiplexing, the second N-plexer comprising: a first port coupled tothe output node of the shared amplification path to receive signalscomprising one or more amplified signals of the first and second RFbands and one or more amplified signals of the first and second IFbands; a second port configured to provide signal(s) comprising one ormore amplified signals of the first and second RF bands; a third portconfigured to provide signal(s) comprising one or more amplified signalsof the first IF band; and a fourth port configured to provide signal(s)comprising one or more amplified signals of the second IF band; a mixerconfigured to multiply a local oscillator (LO) signal with signal(s)comprising the one or more amplified signals of the first and second RFbands to generate a plurality of signals including the one or moresignals of the first and second IF bands; a third N-plexer arranged toperform frequency demultiplexing, the third N-plexer comprising: a firstport configured to receive signal(s) comprising the plurality of signalsgenerated by the mixer; a second port configured to provide signal(s)comprising the one or more signals of the first IF band; and a thirdport configured to provide signal(s) comprising the one or more signalsof the second IF band; a first IF filter arranged in a signal pathbetween second port of the third N-plexer and the second port of thefirst N-plexer, wherein the first IF filter is configured to rejectsignals outside the first IF band and to provide the one or more signalsof the IF band to the first N-plexer; and a second IF filter arranged ina signal path between the third port of the third N-plexer and thefourth port of the first N-plexer, wherein the second IF filter isconfigured to reject signals outside the second IF band and to providethe one or more signals of the second IF band to the first N-plexer.

One embodiment includes a method of amplifying a plurality of signals,wherein the method includes: receiving signal(s) comprising one or moresignals of a first radio frequency (RF) band and one or more signals ofa second RF band at a first port of a first N-plexer; receivingsignal(s) comprising one or more signals of a first intermediatefrequency (IF) band at a second port of the first N-plexer; receivingsignal(s) comprising one or more signals of a second IF band at a fourthport of the first N-plexer; frequency multiplexing the signals of thefirst and second RF bands and signals of the first and second IF bandsto generate multiplexed signals; providing the multiplexed signals at athird port of the first N-plexer; amplifying the multiplexed RF and IFband signals in a shared amplification path to generate one or moreamplified signals of the each of the first and second RF bands and thefirst and second IF bands; receiving signals comprising one or moreamplified signals of the first and second RF bands and one or moreamplified signals of the first and second IF bands at a first port of asecond N-plexer; frequency demultiplexing and providing signal(s)comprising one or more amplified signals of the first and second RFbands at a second port of the second N-plexer; frequency demultiplexingand providing signal(s) comprising one or more amplified signals of thefirst IF band at a third port of the second N-plexer; and frequencydemultiplexing and providing signal(s) comprising one or more amplifiedsignals of the second IF band at a fourth port of the second N-plexer;mixing a local oscillator (LO) signal with signal(s) comprising the oneor more amplified signals of the first and second RF bands to generate aplurality of signals including the one or more signals of the first andsecond IF bands; receiving signal(s) comprising the plurality of signalsat a first port of a third N-plexer (844); frequency demultiplexing andproviding signal(s) comprising the one or more signals of the first IFband at a second port of the third N-plexer (844); and frequencydemultiplexing and providing signal(s) comprising the one or moresignals of the second IF band at a third port of the third N-plexer(844); filtering the one or more signals of the first IF band andproviding the one or more signals of the first IF band to the secondport of the first N-plexer; and filtering the one or more signals of thesecond IF band and providing the one or more signals of the second IFband to the fourth port of the first N-plexer.

One embodiment includes an apparatus, wherein the apparatus includes: ameans for frequency multiplexing comprising: a first port configured toreceive signal(s) comprising one or more signals of a first radiofrequency (RF) band and one or more signals of a second RF band; asecond port configured to receive signal(s) comprising one or moresignals of a first intermediate frequency (IF) band; a fourth portconfigured to receive signal(s) comprising one or more signals of asecond IF band; and a third port configured to provide the signals ofthe first and second RF bands and the signals of the first and second IFbands in a frequency multiplexed fashion; wherein the frequencymultiplexing means is configured to substantially isolate the one ormore signals of the first and second IF bands from the first port; ameans for amplifying having an input node and an output node, whereinthe input node is coupled to the third port of the frequencymultiplexing means; a first means for frequency demultiplexingcomprising: a first port coupled to the output node of the sharedamplification path to receive signals comprising one or more amplifiedsignals of the first and second RF bands and one or more amplifiedsignals of the first and second IF bands; a second port configured toprovide signal(s) comprising one or more amplified signals of the firstand second RF bands; a third port configured to provide signal(s)comprising one or more amplified signals of the first IF band; and afourth port configured to provide signal(s) comprising one or moreamplified signals of the second IF band; a mixer configured to multiplya local oscillator (LO) signal with signal(s) comprising the one or moreamplified signals of the first and second RF bands to generate aplurality of signals including the one or more signals of the first andsecond IF bands; a second means for demultiplexing comprising: a firstport configured to receive signal(s) comprising the plurality of signalsgenerated by the mixer; a second port configured to provide signal(s)comprising the one or more signals of the first IF band; and a thirdport configured to provide signal(s) comprising the one or more signalsof the second IF band; a first IF filter arranged in a signal pathbetween second port of the second demultiplexing means and the secondport of the multiplexing means, wherein the first IF filter isconfigured to reject signals outside the first IF band and to providethe one or more signals of the IF band to the multiplexing means; and asecond IF filter arranged in a signal path between the third port of thesecond demultiplexing means and the fourth port of the multiplexingmeans, wherein the second IF filter is configured to reject signalsoutside the second IF band and to provide the one or more signals of thesecond IF band to the multiplexing means.

BRIEF DESCRIPTION OF THE DRAWINGS

These drawings and the associated description herein are provided toillustrate specific embodiments and are not intended to be limiting.

FIG. 1 is a schematic diagram illustrating a front end of a receiveraccording to an embodiment of the invention in which a sharedamplification path includes both an amplifier and an attenuator.

FIG. 2 is a schematic diagram illustrating a front end of a receiveraccording to an embodiment of the invention wherein an attenuatorresides in a radio frequency signal path outside the sharedamplification path.

FIG. 3 is a schematic diagram illustrating a front end of a receiveraccording to an embodiment of the invention with an attenuator in radiofrequency (RF) signal paths outside the shared amplification path, withmultiple RF and intermediate frequency (IF) bands, and with a singlemixer.

FIG. 4 is a schematic diagram illustrating a front end of a receiveraccording to an embodiment of the invention with attenuators in radiofrequency (RF) signal paths outside the shared amplification path, withmultiple RF and intermediate frequency (IF) bands, and with multiplemixers.

FIG. 5 is a schematic diagram illustrating a front end of a receiveraccording to an embodiment of the invention wherein an attenuatorresides in an intermediate frequency signal path outside the sharedamplification path.

FIG. 6 is a schematic diagram illustrating a front end of a receiveraccording to an embodiment of the invention with attenuators inintermediate frequency (IF) signal paths outside the sharedamplification path, with multiple radio frequency (RF) and IF bands, andwith a single mixer.

FIG. 7 is a schematic diagram illustrating a front end of a receiveraccording to an embodiment of the invention with attenuators inintermediate frequency (IF) signal paths outside the sharedamplification path, with multiple radio frequency (RF) and IF bands, andwith multiple mixers.

FIG. 8 is a schematic diagram illustrating a front end of a receiveraccording to an embodiment of the invention with a shared amplificationpath including both an amplifier and an attenuator, with multiple radiofrequency (RF) and intermediate frequency (IF) bands, and with a singlemixer.

In this description, reference is made to the drawings in which likereference numerals may indicate identical or functionally similarelements.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

A radio receiver has a front end having a shared amplification path forboth radio frequency signals and intermediate frequency signals. In oneexample, the shared amplification path can include a low noise amplifierand an attenuator. By amplifying both radio frequency (RF) signals andintermediate frequency (IF) signals with the same shared amplificationpath, gains in power efficiency, and reductions in cost and circuit sizecan be achieved.

The receiver can be used anywhere that radio receivers are used, suchas, but not limited to, receivers for a global navigation satellitesystem (GNSS) such as the global positioning system (GPS), Glonass,Galilio, or Beidou, cellular telephony, computers, laptops, smartphones, tablets, data communications devices, radios, televisions, cablemodems, set top boxes, digital subscriber line (DSL) modems, satelliteor terrestrial over-the-air broadcasting of data signals or televisionsignals, two-way radios, wireless computer networks such as WiFi (IEEE802.11), bluetooth (IEEE 802.15.1), cordless telephones, radio controltoys, baby monitors, RADAR, repeaters, implantable medical devices,wireless memory cards, and the like.

Although particular embodiments are described herein, other embodimentsof the invention, including embodiments that do not provide all of thebenefits and features set forth herein, will be apparent to those ofordinary skill in the art.

FIG. 1 is a schematic diagram illustrating a front end 106 of asuperheterodyne receiver according to an embodiment of the invention.The receiver can include other components not shown, despreaders,demodulators, impedance transform circuits and the like. For example,impedance transform circuits can be used for impedance matching and/orfor deliberate impedance mismatching. FIG. 1 illustrates an antenna 102and the front end 106. The illustrated front end 106 optionally includesan RF filter 104 and includes a first diplexer 108, a sharedamplification path 110, a second diplexer 112, an optional RF filter120, a mixer 122, an IF filter 124, and an IF filter 130, ananalog-to-digital converter (ADC) 132, and an automatic gain control(AGC) circuit 140.

The illustrated shared amplification path 110 includes a first low-noiseamplifier (LNA) 114, a controllable attenuator 116, and a second LNA118. One of the first LNA or the second LNA 118 can be optional. In theillustrated embodiment, the first LNA 114 and the second LNA 118 areboth fixed gain amplifiers, and gain adjustment is performed by thecontrollable attenuator 116.

Operation of the front end 106 and associated components will now bedescribed. Initially, a top-level overview will be described followed bya more detailed description. An RF signal is applied as an input to thefirst diplexer 108, passes through to the output of the first diplexer108 and to the shared amplification path 110, which amplifies andattenuators the RF signal. The amplified RF signal then passes throughthe second diplexer 112 to the mixer 122, which generates the IF signalby downconversion of the amplified RF signal. The IF signal then passesthrough the first diplexer 108 and is amplified and attenuated by theshared amplification path 110. The amplified IF signal passes throughthe second diplexer 112 to be converted to digital form by the ADC 132,which generates a digital IF signal, which is then monitored by anautomatic gain control (AGC) circuit 140 to control gain by adjustmentof the amount of attenuation by the controllable attenuator 116. Thecontrollable attenuator 116 can be a digital attenuator, that is, adigitally controlled attenuator. Because of the two passes through theshared amplification path 110, the step size of attenuation by thecontrollable attenuator 116 is twice the usual amount.

One or more RF signals is received by the antenna 102. While illustratedwith antennas in FIGS. 1-5, the principles and advantages disclosedherein are also applicable to wired systems. Optionally, an RF filter104 can be included to help filter out undesired signals. In oneexample, the RF filter 104 can be implemented by a surface acoustic wave(SAW) filter, which can assist in filtering out electromagneticinterference (EMI) generated by the receiver. However, other types offilters can be used and will be readily determined by one of ordinaryskill in the art. In certain embodiments, the antenna 102 can correspondto a controlled reception pattern antenna (CRPA) and can have multipleelements, each with a RF front end for beamforming/nulling.

The first diplexer 108 is arranged to perform frequency multiplexing.While illustrated with diplexers 108, 112, the principles and advantagesdisclosed herein are applicable to N-plexers wherein the value of N canvary in a very broad range. When N is equal to 2 as shown in FIG. 1, anN-plexer can be called a diplexer. When N is equal to 3, an N-plexer canbe called a triplexer. When N is equal to 4, an N-plexer can be called aquadplexer, and so on. These N-plexers can be used for either frequencymultiplexing or demultiplexing depending on how they are arranged.N-plexers are frequency selective and are typically implemented withinductors and capacitors, and can include low-pass filters, high-passfilters, band-pass filters, impedance-matching networks, or the like.N-plexers are different from combiners/splitters, which are typicallynot frequency selective. N-plexers have less insertion loss thancombiners/splitters.

The first diplexer 108 includes a first port, which receives one or moresignals of a RF band from the RF filter 104, a second port, whichreceives one or more signals of an IF band from the IF filter 124, and athird port that combines and provides the one or more signals of the RFband and the one or more signals of the IF band as an output. Forexample, the first diplexer 108 can include a high pass filter or bandpass filter for RF from the first port to the third port, and a low passfilter or band pass filter for IF from the second port to the thirdport. The one or more signals of the RF band pass from the first port tothe third port of the first diplexer 108 in a substantially unattenuatedmanner. Advantageously, the first diplexer 108 can substantially isolatethe one or more signals of the IF band from the first port to helpreduce EMI. This reduction in EMI via the first diplexer 108 isimportant in a practical receiver implementation because priorimplementations of receivers, such as those found in reflex receivers,reflectional amplifiers, and the like, would typically produce too muchEMI to implement in a real-world environment.

The shared amplification path 110 has an input node, which is coupled tothe third port of the first diplexer 108, and an output node which iscoupled to the second diplexer 112. The shared amplification path 110advantageously amplifies both RF and IF signals to generate one or moreamplified signals of the RF band and one or more amplified signals ofthe IF band.

The second diplexer 112 is arranged to perform frequency demultiplexingon the one or more amplified signals of the RF band and one or moreamplified signals of the IF band. The second diplexer 112 includes afirst port that receives the one or more amplified signals of the RFband and one or more amplified signals of the IF band from the outputnode of the shared amplification path 110, a second port that providesone or more amplified signals of the RF band as an output, and a thirdport that provides one or more amplified signals of the IF band as anoutput. For example, the second diplexer 112 can include a high passfilter or band pass filter for RF from the first port to the secondport, and a low pass filter or band pass filter for IF from the firstport to the third port.

An RF filter 120 can be optionally inserted in the signal path betweenthe second port of the second diplexer 112 and the mixer 122. The RFfilter 120 can be implemented by a SAW filter, but other types offilters can alternatively be used. The RF filter 120 can provideadditional spectrum isolation. The amount of spectrum isolation can varydepending on the application and on system dynamic range used.

The mixer 122 mixes or multiplies a local oscillator (LO) signal withthe one or more amplified signals of the RF band to generate a pluralityof signals. Multiplication of input signals results in output signalsthat are sum and difference in frequency between the input signals. Inthe context of the mixer 122, the result of mixing includes the desiredone or more IF signals having a frequency that is the difference infrequency between the LO and the one or more amplified signals of the RFband, and also other signals having a frequency that is the sum of theLO and the one or more amplified signals of the RF band. The mixer 122can also provide as an output other signals that are not desired in thiscontext, such as bleed through of the LO and bleed through of thesignals of the RF band. The IF filter 124 rejects those signals outsidethe band of the IF signals, and provides the remaining one or more IFsignals as an input to the second port of the first diplexer 108. The IFfilter 124 can also provide an impedance transform function.

The one or more IF signals pass from the second port to the third portof the first diplexer 108 in a substantially unattenuated manner. Theone or more IF signals are then amplified/attenuated by the amplifiers114, 118 and the controllable attenuator 116 of the shared amplificationpath 110, and one or more amplified IF signals are provided as an inputto the first port of the second diplexer 112.

The one or more amplified IF signals pass from the first port to thethird port of the second diplexer 112 in a substantially unattenuatedmanner. The one or more amplified IF signals can then be filtered by theIF filter 130 for anti-aliasing and provided as an input to the ADC 132.The IF filter 130 can include an impedance transformation. The ADC 132produces a digital IF signal, which is used by downstream portions ofthe receiver, such as despreaders, demodulators, or the like. However,in alternative embodiments, the subsequent processing of IF signals canbe performed in the analog domain. In the illustrated embodiment, theAGC circuit 140 monitors the digital IF signal and adjusts theattenuation of the controllable attenuator 116 such that the digital IFsignal efficiently uses the input range of the ADC 132.

FIG. 2 is a schematic diagram illustrating a front end 206 of asuperheterodyne receiver according to another embodiment of theinvention. The receiver can include other components not shown,despreaders, demodulators, impedance transform circuits and the like.The front end 206 features an attenuator outside of a sharedamplification path 210. FIG. 2 illustrates the antenna 102 and the frontend 206. To avoid repetition of description, components having the sameor similar function may be referenced by the same reference number.

The illustrated front end 206 optionally includes the RF filter 104 andincludes the first diplexer 108, the shared amplification path 210, thesecond diplexer 112, a controllable attenuator 216, the optional RFfilter 120, the mixer 122, the IF filter 124, the IF filter 130, the ADC132, and the AGC circuit 140. The operation of the front end 206 of FIG.2 is basically the same as the front-end 106 of FIG. 1 except for theoperation of the controllable attenuator 216.

The first diplexer 208 is arranged to perform frequency multiplexing. Afirst port of the first diplexer 208 receives one or more signals of anRF band. A second port of the first diplexer receives one or moresignals of an IF band from the output of the IF filter 224. A third portof the first diplexer 208 combines and provides the one or more signalsof the RF band and the one or more signals of the IF band as an outputin a substantially unattenuated manner. Advantageously, the firstdiplexer 208 substantially isolates the one or more signals of the IFband from the first port to help reduce EMI.

The shared amplification path 210 has an input node and an output node,and amplifies signals from both the RF band and the IF band. The inputnode is coupled to the third port of the first diplexer 208 to receivethe signals to be amplified.

The second diplexer 212 is arranged to perform frequency demultiplexing.A first port of the second diplexer 212 is coupled to the output node ofthe shared amplification path 210 and receives one or more amplifiedsignals of the RF band and one or more amplified signals of the IF band.A second port of the second diplexer 212 provides one or more amplifiedsignals of the RF band as an output, and a third port of the seconddiplexer 212 provides one or more amplified signals of the IF band as anoutput.

The one or more amplified signals of the RF band are attenuated by thecontrollable attenuator 216, which is disposed in a signal path betweenthe second port of the second diplexer 212 and an input of the mixer222. The controllable attenuator is sets an overall gain of the one ormore amplified signals of the RF band, which indirectly controls thegain of one or more signals of an IF band, which are downconverted fromthe one or more signals of the RF band. It should be noted that incontrast to the controllable attenuator 116 (FIG. 1), the amount ofattenuation provided by the controllable attenuator 216 is not doubled.

The mixer 222 multiplies a local oscillator signal (LO) with the one ormore amplified signals of the RF band to generate a plurality of signalsthat includes the one or more signals of the IF band. An optional RFfilter 220 can be disposed in a signal path between the second port ofthe second diplexer 212 and the mixer 222. The RF filter 220 and thecontrollable attenuator 216 can be arranged in any order between thesecond port of the second diplexer 212 and the mixer 222.

The IF filter 224 is disposed in a signal path between an output of themixer 222 and the second port of the first diplexer 208. The IF filter224 rejects signals outside of the IF band and provides the one or moresignals of the IF band to the first diplexer 208. The first diplexer 208passes the one or more signals of the IF band from the second port tothe third port, and the shared amplification path 210 amplifies the oneor more signals of the IF band. The one or more amplified signals of theIF band are then passed from the first port of the second diplexer 212to the third port of the second diplexer 212, and provided as an inputto the IF filter 130, then converted to a digital IF signal by the ADC132 and provided to downstream portions of the receiver. The digital IFsignal is also monitored by the AGC circuit 140 to adjust the amount ofattenuation provided by the controllable attenuator 216.

FIG. 3 is a schematic diagram illustrating a front end 306 and othercomponents for a superheterodyne receiver according to anotherembodiment of the invention. The front end 306 receives signals frommultiple RF bands and generates signals for multiple IF bands andfeatures attenuators outside of a shared amplification path 310 forindependent gain adjustment of the signals of the multiple bands. Whileillustrated in the context of two RF bands and two IF bands, theprinciples and advantages disclosed herein can be extended to additionalnumbers of RF bands and IF bands. The illustrated embodiment isconsiderably more compact and power efficient than a front end using twoseparate mixers and having four amplification paths (one for each RF andIF band).

FIG. 3 illustrates the antenna 102 and the front end 306. The front end306 includes a triplexer 308, the shared amplification path 310, aquadplexer 312, a first controllable attenuator 316, a secondcontrollable attenuator 317, a first diplexer 342, a mixer 322, a seconddiplexer 344, a first IF filter 324, a second IF filter 325, IF filters330, 331, ADCs 332, 333 and AGC circuits 340, 341. The receiver caninclude other components not shown, such as RF filters, despreaders,demodulators, impedance transform circuits and the like. For example,SAW filters can be incorporated into the triplexer 308 to help reduceEMI.

The triplexer 308 is arranged to perform frequency multiplexing and hasa first port, a second port, a third port, and a fourth port. The firstport receives signals from an antenna or other RF source, such as acable. The received signals include signals from at least two differentRF bands. For example, in the context of GPS, a GPS receiver can receivesignals in the L1 band, which is 1575.42 megahertz (MHz), and signals inthe L2 band 1227.60 MHz. The GPS satellites transmit at the samefrequencies so that multiple different RF signals per band willgenerally be received by a GPS receiver. The second port receives one ormore signals of a first IF band from the output of the first IF filter324. The fourth port receive one or more signals of a second IF bandfrom the second IF filter 325. The third port of the first diplexer 208combines and provides the one or more signals of the first and second RFbands and the one or more signals of the first and second IF bands as anoutput in a substantially unattenuated manner. Advantageously, the firstdiplexer 208 substantially isolates the one or more signals of the firstand second IF bands from the first port to help reduce EMI.

The shared amplification path 310 has an input node and an output nodeand has at least one amplifier 314, which amplifies both RF signals andIF signals. The input node is coupled to the third port of the triplexer308 to receive signals for amplification. The output node is coupled tothe quadplexer 312.

The quadplexer 312 is arranged to perform frequency demultiplexing andhas a first port, a second port, a third port, a fourth port, and afifth port. The first port is coupled to the output node of the sharedamplification path 310 and receives one or more amplified signals of thefirst and second RF bands and one or more amplified signals of the firstand second IF bands. The second port provides the one or more amplifiedsignals of the first RF band as an output. The third port provides theone or more amplified signals of the first IF band as an output. Thefourth port provides the one or more amplified signals of the second RFband as an output. The fifth port provides the one or more amplifiedsignals of the second IF band as an output.

The first and second controllable attenuators 316, 317 are arranged in asignal path between the second and fourth ports, respectively, of thequadplexer 312 and the first and second ports of the first diplexer 342.The first controllable attenuator 316 sets an overall gain of the one ormore amplified signals of the first RF band and the second controllableattenuator 317 sets an overall gain of the one or more amplified signalof the second RF band. In the illustrated front end 306, each RF bandhas a separate attenuator for individual gain adjustment of the RF gain,which affects the IF signal level as well.

The first diplexer 342 is arranged to perform frequency multiplexing andhas a first port, a second port, and a third port. The first portreceives the one or more amplified signals of a first RF band, thesecond port receives the one or more amplified signals of a second RFband, and the third port combines and provides the one or more amplifiedsignals of the first RF band and the one or more amplified signals ofthe second RF band as an output in a substantially unattenuated manner.

The mixer 322 has an input coupled to the third port of the firstdiplexer 342 and multiplies a LO signal with the one or more amplifiedsignals of the first and second RF bands to generate a plurality ofsignals including the one or more signals of the first and second IFbands. Because the first and second RF bands are at differentfrequencies, the first and second IF bands will also be at differentfrequencies. The results of multiplication by the mixer 322 can includeother signals that are not desired, such as bleed through of the LOsignal, bleed through of the signals of the first and second RF bandsand signals having a frequencies that are the sum of the LO frequencyand frequencies of the first and second RF bands.

The second diplexer 344 is arranged to perform frequency demultiplexingand has a first port, a second port, and a third port. The seconddiplexer 344 receives the signals from the mixer 322 and separates thesignals from the first IF band from signals from the second IF band. Thesignals from the first IF band are provided as an output on the secondport, and the signals from the second IF band are provided as an outputon the third port. However, other signals may accompany the signals fromthe first IF band and the second IF band.

The first IF filter 324 is arranged in a signal path between second portof the second diplexer 344 and the second port of the triplexer 308. Thefirst IF filter 324 filters the one or more signals of the first IF bandto reject those signals outside the first IF band and provides the oneor more signals of the first IF band to the triplexer 308.

The second IF filter 325 is arranged in a signal path between an outputof the mixer 322 and the fourth port of the triplexer 308. The second IFfilter 325 filters the one or more signals of the second IF band toreject those signals outside the second IF band and provides the one ormore signals of the second IF band to the triplexer 308.

The triplexer 308 performs frequency multiplexing to combine the signalsof the first and second IF bands with the RF signals from the firstport, and to provide the combined signals to the shared amplificationpath 310 via the third port of the triplexer. In this manner, the sharedamplification path 310 can amplify the signals of the first and secondRF bands and the first and second IF bands.

The amplified signals of the first and second bands are demultiplexedfrom the other signals by the quadplexer 312, which provides theamplified signals of the first band to the IF filter 330 and theamplified signals of the second band to the IF filter 331. The IFfilters 330, 331 can provide anti-aliasing filtering and can alsoinclude an impedance transformation. The ADCs 332, 333 produces digitalIF signals, which are used by downstream portions of the receiver, suchas despreaders, demodulators, or the like. The AGC circuits 340. 341monitor the digital IF signals and adjusts the attenuation of thecontrollable attenuators 316, 317 such that the digital IF signalsefficiently use the input range of the ADCs 332, 333.

FIG. 4 is a schematic diagram illustrating a front end 406 and othercomponents for a superheterodyne receiver according to anotherembodiment of the invention. Similar to the front end 306 (FIG. 3), thefront end 406 receives and amplifies signals from multiple RF and IFbands. However, the front end 406 uses multiple mixers instead of asingle mixer. While illustrated in the context of two RF bands and twoIF bands, the principles and advantages disclosed herein can be extendedto additional numbers of RF bands and IF bands. The illustratedembodiment is more compact and power efficient than a front end havingfour amplification paths (one for each RF and IF band).

FIG. 4 illustrates the antenna 102 and the front end 406. The receivercan include other components not shown, such as RF filters, despreaders,demodulators, impedance transform circuits and the like. The front end406 includes a triplexer 408, a shared amplification path 410, aquadplexer 412, a first controllable attenuator 416, a secondcontrollable attenuator 417, a first mixer 422, a second mixer 423, afirst IF filter 424, a second IF filter 425, IF filters 430, 431, ADCs432, 433 and AGC circuits 440, 441.

The triplexer 408 is arranged to perform frequency multiplexing and hasa first port, a second port, a third port, and a fourth port. The firstport receives signals from an antenna or other RF source, such as acable. The received signals include signals from at least two differentRF bands. The second port receives one or more signals of a first IFband from the output of the first IF filter 424. The fourth port receiveone or more signals of a second IF band from the second IF filter 425.The third port of the first diplexer 208 combines and provides the oneor more signals of the first and second RF bands and the one or moresignals of the first and second IF bands as an output in a substantiallyunattenuated manner. Advantageously, the first diplexer 208substantially isolates the one or more signals of the first and secondIF bands from the first port to help reduce EMI.

The shared amplification path 410 has an input node and an output nodeand has at least one amplifier 414, which amplifies both RF signals andIF signals. The input node is coupled to the third port of the triplexer408 to receive signals for amplification. The output node is coupled tothe quadplexer 412.

The quadplexer 412 is arranged to perform frequency demultiplexing andhas a first port, a second port, a third port, a fourth port, and afifth port. The first port is coupled to the output node of the sharedamplification path 410 and receives one or more amplified signals of thefirst and second RF bands and one or more amplified signals of the firstand second IF bands. The second port provides the one or more amplifiedsignals of the first RF band as an output. The third port provides theone or more amplified signals of the first IF band as an output. Thefourth port provides the one or more amplified signals of the second RFband as an output. The fifth port provides the one or more amplifiedsignals of the second IF band as an output.

The first and second controllable attenuators 416, 417 are arranged in asignal path between the second and fourth ports, respectively, of thequadplexer 412 and the first and second mixers 422, 423. The firstcontrollable attenuator 416 sets an overall gain of the one or moreamplified signals of the first RF band and the second controllableattenuator 417 sets an overall gain of the one or more amplified signalof the second RF band. In the illustrated front end 406, each RF bandhas a separate attenuator for individual gain adjustment of the RF gain,which affects the IF signal level as well.

The first mixer 422 has an input coupled to the first controllableattenuator 416 and multiplies a first LO signal with the one or moreamplified signals of the first RF band to generate a plurality ofsignals including the one or more signals of the first IF band. Theresults of multiplication by the first mixer 422 can include othersignals that are not desired.

The second mixer 423 has an input coupled to the second controllableattenuator 417 and multiplies a second LO signal with the one or moreamplified signals of the second RF band to generate a plurality ofsignals including the one or more signals of the second IF band. Theresults of multiplication by the second mixer 423 can include othersignals that are not desired. The second LO signal has a differentfrequency than the first LO signal.

The first IF filter 424 is arranged in a signal path between the firstmixer 422 and the second port of the triplexer 408. The first IF filter424 filters the one or more signals of the first IF band to reject thosesignals outside the first IF band and provides the one or more signalsof the first IF band to the triplexer 408.

The second IF filter 425 is arranged in a signal path between the secondmixer 423 and the fourth port of the triplexer 408. The second IF filter425 filters the one or more signals of the second IF band to rejectthose signals outside the second IF band and provides the one or moresignals of the second IF band to the triplexer 408.

The triplexer 408 performs frequency multiplexing to combine the signalsof the first and second IF bands with the RF signals from the firstport, and to provide the combined signals to the shared amplificationpath 410 via the third port of the triplexer.

The amplified signals of the first and second bands are demultiplexedfrom the other signals by the quadplexer 412, which provides theamplified signals of the first band to the IF filter 430 and theamplified signals of the second band to the IF filter 431. The IFfilters 430, 431 can provide anti-aliasing filtering and can alsoinclude impedance transformations. The ADCs 432, 433 produces digital IFsignals, which are used by downstream portions of the receiver, such asdespreaders, demodulators, or the like. The AGC circuits 440, 441monitor the digital IF signals and adjusts the attenuation of thecontrollable attenuators 416, 417 such that the digital IF signalsefficiently use the input range of the ADCs 432, 433.

FIG. 5 is a schematic diagram illustrating a front end 506 of a receiveraccording to an embodiment of the invention. The front end 506 can besimilar to the front end 206 (FIG. 2) except that the AGC circuit 140controls an attenuator 516 residing in an intermediate frequency signalpath, rather than in an RF signal path as shown in the configuration ofFIG. 2. To avoid repetition of description, components having the sameor similar function may be referenced by the same reference number.

FIG. 6 is a schematic diagram illustrating a front end 606 of a receiveraccording to an embodiment of the invention. The front end 606 can besimilar to the front end 306 (FIG. 3) except that the AGC circuits 340,341 control attenuators 616, 617 residing in intermediate frequency (IF)signal paths, rather than in RF signal paths as shown in theconfiguration of FIG. 3.

FIG. 7 is a schematic diagram illustrating a front end 706 of a receiveraccording to an embodiment of the invention. The front end 706 can besimilar to the front end 406 (FIG. 4) except that the AGC circuits 440,441 control attenuators 716, 717 in IF signal paths, rather than in RFsignal paths as shown in the configuration of FIG. 4. To avoidrepetition of description, components having the same or similarfunction may be referenced by the same reference number.

FIG. 8 is a schematic diagram illustrating a front end 806 and othercomponents for a superheterodyne receiver according to anotherembodiment of the invention. The front end 806 receives signals frommultiple RF bands and generates signals for multiple IF bands. The frontend 806 features an attenuator within a shared amplification path 810for independent gain adjustment of the signals of the multiple bands.While illustrated in the context of two RF bands and two IF bands, theprinciples and advantages disclosed herein can be extended to additionalnumbers of RF bands and IF bands and to separate mixers for thedifferent RF bands, and to combinations of separate mixers for separateRF bands and mixers handling more than one RF band.

FIG. 8 illustrates the antenna 102, the front end 806, IF filters 830,831, ADCs 832, 833 and an AGC circuit 840. The receiver can includeother components not shown, such as RF filters, despreaders,demodulators, impedance transform circuits and the like. For example, aSAW filter can be used between the antenna 102 and the front end 806.The front end 806 includes a first triplexer 808, the sharedamplification path 810, a second triplexer 812, a mixer 822, a diplexer844, a first IF filter 824, and a second IF filter 825.

The first triplexer 808 is arranged to perform frequency multiplexingand has a first port, a second port, a third port, and a fourth port.The first port receives signals from an antenna or other RF source, suchas a cable. The received signals include signals from at least twodifferent RF bands. The second port receives one or more signals of afirst IF band from the output of the first IF filter 824. The fourthport receive one or more signals of a second IF band from the second IFfilter 825. The third port of the first diplexer 208 combines andprovides the one or more signals of the first and second RF bands andthe one or more signals of the first and second IF bands as an output ina substantially unattenuated manner. Advantageously, the first diplexer208 substantially isolates the one or more signals of the first andsecond IF bands from the first port to help reduce EMI.

The shared amplification path 810 has an input node and an output nodeand has at least one amplifier 814, which amplifies both RF signals andIF signals. In one embodiment, the shared amplification path 810includes at least one amplifier and at least one controllableattenuator. In an alternative embodiment, the shared amplification path810 includes a variable gain amplifier without an attenuator. In analternative embodiment, the shared amplification path 810 includes afixed gain amplifier without an attenuator. The amplifier can be an LNA.In certain embodiments, the amplifiers described herein can be solidstate semiconductor or transistor-based amplifiers. The input node iscoupled to the third port of the first triplexer 808 to receive signalsfor amplification. The output node is coupled to the second triplexer812.

The second triplexer 812 is arranged to perform frequency demultiplexingand has a first port, a second port, a third port, and a fourth port.The first port is coupled to the output node of the shared amplificationpath 810 and receives one or more amplified signals of the first andsecond RF bands and one or more amplified signals of the first andsecond IF bands. The second port provides the one or more amplifiedsignals of the first and second RF bands as an output. The third portprovides the one or more amplified signals of the first IF band as anoutput. The fourth port provides the one or more amplified signals ofthe second IF band as an output.

The mixer 822 has an input coupled to the second port of the secondtriplexer 812 and multiplies a LO signal with the one or more amplifiedsignals of the first and second RF bands to generate a plurality ofsignals including the one or more signals of the first and second IFbands.

The diplexer 844 is arranged to perform frequency demultiplexing and hasa first port, a second port, and a third port. The diplexer 844 receivesthe signals from the mixer 822 and separates the signals from the firstIF band from signals from the second IF band. The signals from the firstIF band are provided as an output on the second port, and the signalsfrom the second IF band are provided as an output on the third port.

The first IF filter 824 is arranged in a signal path between second portof the diplexer 844 and the second port of the first triplexer 808. Thefirst IF filter 824 filters the one or more signals of the first IF bandto reject those signals outside the first IF band and provides the oneor more signals of the first IF band to the first triplexer 808.

The second IF filter 825 is arranged in a signal path between an outputof the mixer 822 and the fourth port of the first triplexer 808. Thesecond IF filter 825 filters the one or more signals of the second IFband to reject those signals outside the second IF band and provides theone or more signals of the second IF band to the first triplexer 808.

The first triplexer 808 performs frequency multiplexing to combine thesignals of the first and second IF bands with the RF signals from thefirst port, and to provide the combined signals to the sharedamplification path 810 via the third port of the first triplexer 808. Inthis manner, the shared amplification path 810 can amplify the signalsof the first and second RF bands and the first and second IF bands.

The amplified signals of the first and second bands are demultiplexedfrom the other signals by the second triplexer 812, which provides theamplified signals of the first band to the IF filter 830 and theamplified signals of the second band to the IF filter 831. The IFfilters 830, 831 can provide anti-aliasing filtering and can alsoinclude an impedance transformation. The ADCs 832, 833 produces digitalIF signals, which are used by downstream portions of the receiver, suchas despreaders, demodulators, or the like. The AGC circuit 840 monitorsthe digital IF signals and adjusts the attenuation of the controllableattenuator of the shared amplification path 810 such that the digital IFsignals efficiently use the input range of the ADCs 832, 833.

As used herein, the term “substantially” intends that the modifiedcharacteristic needs not be absolute, but is close enough so as toachieve the advantages of the characteristic. For example, in thecontext of N-plexers, “substantially unattenuated” can mean less than2.5 decibels (dB) of insertion loss, less than 2.0 dB of insertion loss,less than 1.5 dB of insertion loss, less than 1.0 dB of insertion loss,or less. In another example, “substantially isolate” can mean isolationof at least 10 dB, 20 dB, 30 dB, or more.

The foregoing description and following claims may refer to elements orfeatures as being “connected” or “coupled” together. As used herein,unless expressly stated to the contrary, “connected” means that oneelement/feature is directly or indirectly connected to anotherelement/feature, and not necessarily mechanically. Likewise, unlessexpressly stated to the contrary, “coupled” means that oneelement/feature is directly or indirectly coupled to anotherelement/feature, and not necessarily mechanically. Thus, although thedrawings illustrate various examples of arrangements of elements andcomponents, additional intervening elements, devices, features, orcomponents may be present in an actual embodiment.

Various embodiments have been described above. Although described withreference to these specific embodiments, the descriptions are intendedto be illustrative and are not intended to be limiting. Variousmodifications and applications may occur to those skilled in the art.

What is claimed is:
 1. An apparatus comprising: a first N-plexerarranged to perform frequency multiplexing, the first N-plexercomprising: a first port configured to receive signal(s) comprising oneor more signals of a first radio frequency (RF) band; a second portconfigured to receive signal(s) comprising one or more signals of afirst intermediate frequency (IF) band; and a third port configured toprovide signals comprising the one or more signals of the first RF bandand the one or more signals of the first IF band; wherein the firstN-plexer is configured to substantially isolate the one or more signalsof the first IF band from the first port; a shared amplification pathhaving an input node and an output node, wherein the input node iscoupled to the third port of the first N-plexer, wherein the sharedamplification path comprises an amplifier configured to amplify signalsfrom at least both the first RF band and the first IF band; a secondN-plexer arranged to perform frequency demultiplexing, the secondN-plexer comprising: a first port coupled to the output node of theshared amplification path, the first port configured to receive signalscomprising the one or more amplified signals of the first RF band andthe one or more amplified signals of the first IF band; a second portconfigured to provide signal(s) comprising the one or more amplifiedsignals of the first RF band; and a third port configured to providesignal(s) comprising the one or more amplified signals of the first IFband, wherein the first port, the second port, and the third port aredifferent ports; a mixer configured to multiply a local oscillator (LO)signal with signal(s) comprising the one or more amplified signals ofthe first RF band to generate a plurality of signals including the oneor more signals of the first IF band; a first controllable attenuatorarranged in a signal path between the second port of the second N-plexerand an input of the mixer, wherein the first controllable attenuator isconfigured to set an overall gain of the one or more amplified signalsof the first RF band; and a first IF filter arranged in a signal pathbetween an output of the mixer and the second port of the firstN-plexer, wherein the first IF filter is configured to filter the one ormore signals of the first IF band and to provide the one or more signalsof the first IF band to the first N-plexer.
 2. The apparatus of claim 1,further comprising a surface acoustic wave (SAW) filter disposed in asignal path between the antenna and the first port of the firstN-plexer.
 3. The apparatus of claim 1, wherein the apparatus comprises afront-end of a superheterodyne receiver, the apparatus furthercomprising: an analog-to-digital converter configured to convert the oneor more amplified signals of the IF band from analog to digital togenerate a digital IF signal; and an automatic gain control (AGC)circuit configured to control an amount of attenuation of the firstcontrollable attenuator based at least partly on a signal strength ofthe digital IF signal.
 4. The apparatus of claim 1, further comprising:a second controllable attenuator; a third N-plexer arranged to performfrequency multiplexing; a fourth N-plexer arranged to perform frequencydemultiplexing; and a second IF filter; wherein the first N-plexerfurther comprises a fourth port configured to receive signal(s)comprising one or more signals of a second IF band, wherein the signalsreceived by the first port of the first N-plexer further comprise one ormore signals of a second RF band; wherein the signals provided by thethird port of the first N-plexer further comprise the one or moresignals of the second RF band; and wherein the first N-plexer is furtherconfigured to substantially isolate the one or more signals of thesecond IF band from the first port; wherein the second N-plexer furthercomprises: a fourth port configured to provide signal(s) comprising oneor more amplified signals of the second RF band; and a fifth portconfigured to provide signal(s) comprising one or more amplified signalsof the second IF band; wherein the second controllable attenuator isarranged in a signal path between the fourth port of the second N-plexerand the mixer, wherein the second controllable attenuator is configuredto set an overall gain of the one or more amplified signals of thesecond RF band; wherein the third N-plexer comprises: a first portconfigured to receive signal(s) comprising the one or more amplifiedsignals of the first RF band; a second port configured to receivesignal(s) comprising the one or more amplified signals of the second RFband; and a third port configured to provide signals comprising the oneor more amplified signals of the first RF band and the one or moreamplified signals of the second RF band; wherein the signal(s)multiplied by the LO signal by the mixer further comprise the one ormore amplified signals of the second RF band, wherein the plurality ofsignals generated by the mixer further includes one or more signals ofthe second IF band; wherein the fourth N-plexer comprises: a first portconfigured to receive signal(s) comprising the plurality of signalsgenerated by the mixer; a second port configured to provide signal(s)comprising the one or more signals of the first IF band; a third portconfigured to provide signal(s) comprising the one or more signals ofthe second IF band; wherein the first IF filter is arranged in a signalpath between second port of the fourth N-plexer and the second port ofthe first N-plexer; wherein the second IF filter is arranged in a signalpath between the third port of the fourth N-plexer and the fourth portof the first N-plexer, wherein the second IF filter is configured tofilter the one or more signals of the second IF band and to provide theone or more signals of the second IF band to the first N-plexer.
 5. Theapparatus of claim 4, further comprising one or more surface acousticwave (SAW) filters incorporated into the first N-plexer.
 6. Theapparatus of claim 4, wherein the apparatus comprises a front-end of asuperheterodyne receiver, the apparatus further comprising: a firstanalog-to-digital converter configured to convert the one or moreamplified signals of the IF band from analog to digital to generate afirst digital IF signal; a first automatic gain control (AGC) circuitconfigured to control an amount of attenuation of the first controllableattenuator based at least partly on a signal strength of the firstdigital IF signal; a second analog-to-digital converter configured toconvert the one or more amplified signals of the second IF band fromanalog to digital to generate a second digital IF signal; and a secondAGC circuit configured to control an amount of attenuation of the secondcontrollable attenuator based at least partly on a signal strength ofthe second digital IF signal.
 7. The apparatus of claim 1, furthercomprising: a second controllable attenuator; a second mixer; and asecond IF filter; wherein the first N-plexer further comprises a fourthport configured to receive signal(s) comprising one or more signals of asecond IF band, wherein the signals received by the first port of thefirst N-plexer further comprise one or more signals of a second RF band;wherein the signals provided by the third port of the first N-plexerfurther comprise the one or more signals of the second RF band; andwherein the first N-plexer is further configured to substantiallyisolate the one or more signals of the second IF band from the firstport; wherein the second N-plexer further comprises: a fourth portconfigured to provide signal(s) comprising one or more amplified signalsof the second RF band; and a fifth port configured to provide signal(s)comprising one or more amplified signals of the second IF band; whereinthe second controllable attenuator is arranged in a signal path betweenthe fourth port of the second N-plexer and the second mixer, wherein thesecond controllable attenuator is configured to set an overall gain ofthe one or more amplified signals of the second RF band; wherein thesecond mixer is configured to multiply a second LO signal with signal(s)comprising one or more amplified signals of a second RF band to generatea plurality of signals including one or more signals of a second IFband; wherein the first IF filter is arranged in a signal path betweenthe mixer and the second port of the first N-plexer; wherein the secondIF filter is arranged in a signal path between the second mixer and thefourth port of the first N-plexer, wherein the second IF filter isconfigured to filter the one or more signals of the second IF band andto provide the one or more signals of the second IF band to the firstN-plexer.
 8. The apparatus of claim 7, further comprising one or moresurface acoustic wave (SAW) filters incorporated into the firstN-plexer.
 9. The apparatus of claim 7, wherein the apparatus comprises afront-end of a superheterodyne receiver, the apparatus furthercomprising: a first analog-to-digital converter configured to convertthe one or more amplified signals of the IF band from analog to digitalto generate a first digital IF signal; a first automatic gain control(AGC) circuit configured to control an amount of attenuation of thefirst controllable attenuator based at least partly on a signal strengthof the first digital IF signal; a second analog-to-digital converterconfigured to convert the one or more amplified signals of the second IFband from analog to digital to generate a second digital IF signal; anda second AGC circuit configured to control an amount of attenuation ofthe second controllable attenuator based at least partly on a signalstrength of the second digital IF signal.
 10. A method of amplifying aplurality of signals, the method comprising: receiving signal(s)comprising one or more signals of a first radio frequency (RF) band at afirst port of a first N-plexer; receiving signal(s) comprising one ormore signals of a first intermediate frequency (IF) band at a secondport of the first N-plexer; frequency multiplexing the signals of the RFband and the IF band to generate multiplexed signals; providing themultiplexed RF and IF band signals at a third port of the firstN-plexer; amplifying the multiplexed RF and IF band signals in a sharedamplification path to generate one or more amplified signals of the RFband and one or more amplified signals of the IF band, wherein theshared amplification path comprises, wherein the shared amplificationpath comprises an amplifier; receiving signals comprising the one ormore amplified signals of the first RF band and the one or moreamplified signals of the first IF band at a first port of a secondN-plexer; frequency demultiplexing the one or more amplified signals ofthe first RF band and the one or more amplified signals of the first IFband using the second N-plexer; providing signal(s) comprising the oneor more amplified signals of the first RF band at a second port of thesecond N-plexer; providing signal(s) comprising the one or moreamplified signals of the first IF band at a third port of the secondN-plexer at a third port of the second N-plexer, wherein the first port,the second port, and the third port are different ports; controlling afirst attenuator to set an overall gain of the one or more amplifiedsignals of the first RF band; mixing a local oscillator (LO) signal withsignal(s) comprising the one or more amplified signals of the first RFband to generate a plurality of signals including the one or moresignals of the first IF band; and filtering the one or more signals ofthe first IF band and providing the one or more signals of the first IFband to the first N-plexer.
 11. The method of claim 10, furthercomprising filtering signals with a surface acoustic wave (SAW) filter,wherein the SAW filter is disposed in a signal path between the antennaand the first port of the first N-plexer.
 12. The method of claim 10,further comprising: converting the one or more amplified signals of theIF band from analog to digital to generate a digital IF signal; andcontrolling an amount of attenuation of the first controllableattenuator based at least partly on a signal strength of the digital IFsignal.
 13. The method of claim 10, further comprising: wherein thefirst N-plexer further comprises a fourth port; wherein the secondN-plexer further comprises a fourth port and a fifth port; receivingsignal(s) comprising one or more signals of a second IF band at thefourth port of the first N-plexer; wherein the signals received by thefirst port of the first N-plexer further comprise one or more signals ofa second RF band at the first port of first N-plexer; wherein thesignals provided by the third port of the first N-plexer furthercomprise the one or more signals of the second RF band; wherein thefirst N-plexer is further configured to substantially isolate the one ormore signals of the second IF band from the first port; providingsignal(s) comprising one or more amplified signals of the second RF bandat the fourth port of the second N-plexer; providing signal(s)comprising one or more amplified signals of the second IF band at thefifth port of the second N-plexer; controlling a second attenuator toset an overall gain of the one or more amplified signals of the secondRF band; receiving signal(s) comprising the one or more amplifiedsignals of the first RF band at a first port of a third N-plexer whereinthe third N-plexer is arranged to perform frequency multiplexing;receiving signal(s) comprising the one or more amplified signals of asecond RF band at a second port of the third N-plexer; providing signalscomprising the one or more amplified signals of the first RF band andthe one or more amplified signals of the second RF band at a third portof the third N-plexer; wherein mixing further comprises mixing the LOsignal with the one or more amplified signals of the second RF band,wherein the plurality of signals generated by mixing further includesone or more signals of the second IF band; receiving signal(s)comprising the plurality of signals generated by the mixer at a firstport of a fourth N-plexer, wherein the fourth N-plexer is arranged toperform frequency demultiplexing; providing signal(s) comprising the oneor more signals of the first IF band at a second port of the fourthN-plexer; providing signal(s) comprising the one or more signals of thesecond IF band at a third port of the fourth N-plexer; and filtering theone or more signals of the second IF band and providing the one or moresignals of the second IF band to the first N-plexer.
 14. The method ofclaim 13, wherein one or more surface acoustic wave (SAW) filters areincorporated into the first N-plexer.
 15. The method of claim 13,further comprising: converting the one or more amplified signals of theIF band from analog to digital to generate a first digital IF signal;controlling an amount of attenuation of the first controllableattenuator based at least partly on a signal strength of the firstdigital IF signal; converting the one or more amplified signals of thesecond IF band from analog to digital to generate a second digital IFsignal; and controlling an amount of attenuation of the secondcontrollable attenuator based at least partly on a signal strength ofthe second digital IF signal.
 16. The method of claim 10, furthercomprising: wherein the first N-plexer further comprises a fourth port;wherein the second N-plexer further comprises a fourth port and a fifthport; receiving signal(s) comprising one or more signals of a second IFband at the fourth port of the first N-plexer; wherein the signalsreceived by the first port of the first N-plexer further comprise one ormore signals of a second RF band; wherein the signals provided by thethird port of the first N-plexer further comprise the one or moresignals of the second RF band; wherein the first N-plexer is furtherconfigured to substantially isolate the one or more signals of thesecond IF band from the first port; providing signal(s) comprising oneor more amplified signals of the second RF band at a fourth port of thesecond N-plexer; and providing signal(s) comprising one or moreamplified signals of the second IF band at a fifth port of the secondN-plexer; controlling a second attenuator to set an overall gain of theone or more amplified signals of the second RF band; mixing the secondLO signal with signal(s) comprising the one or more amplified signals ofthe second RF band to generate a plurality of signals including the oneor more signals of the second IF band; and filtering the one or moresignals of the second IF band and providing the one or more signals ofthe second IF band to the first N-plexer.
 17. The method of claim 16,further comprising one or more surface acoustic wave (SAW) filtersincorporated into the first N-plexer.
 18. The method of claim 16,further comprising: converting the one or more amplified signals of theIF band from analog to digital to generate a first digital IF signal;controlling an amount of attenuation of the first controllableattenuator based at least partly on a signal strength of the firstdigital IF signal; converting the one or more amplified signals of thesecond IF band from analog to digital to generate a second digital IFsignal; and controlling an amount of attenuation of the secondcontrollable attenuator based at least partly on a signal strength ofthe second digital IF signal.
 19. An apparatus for amplifying aplurality of signals, the apparatus comprising: a means for frequencymultiplexing configured to: receive signal(s) comprising one or moresignals of a first radio frequency (RF) band at a first port; receivesignal(s) comprising one or more signals of a first intermediatefrequency (IF) band at a second port; and provide signals comprising theone or more signals of the first RF band and the one or more signals ofthe first IF band at a third port; wherein the frequency multiplexingmeans is configured to substantially isolate the one or more signals ofthe first IF band from the first port; a shared amplification pathhaving an input node and an output node, wherein the input node iscoupled to the third port of the frequency multiplexing means, whereinthe shared amplification path comprises an amplifier configured toamplify signals from at least both the first RF band and the first IFband; a means for frequency demultiplexing configured to: to receivesignals comprising the one or more amplified signals of the first RFband and the one or more amplified signals of the first IF band at afirst port; provide signal(s) comprising the one or more amplifiedsignals of the first RF band at a second port; and provide signal(s)comprising the one or more amplified signals of the first IF band at athird port, wherein the first port, the second port, and the third portare different ports; a mixer configured to multiply a local oscillator(LO) signal with signal(s) comprising the one or more amplified signalsof the first RF band to generate a plurality of signals including theone or more signals of the first IF band; a first controllableattenuator arranged in a signal path between the second port of thefrequency demultiplexing means and an input of the mixer, wherein thefirst controllable attenuator is configured to set an overall gain ofthe one or more amplified signals of the first RF band; and a first IFfilter arranged in a signal path between an output of the mixer and thesecond port of the frequency demultiplexing means, wherein the first IFfilter is configured to filter the one or more signals of the first IFband and to provide the one or more signals of the first IF band to thefrequency demultiplexing means.